Start adding release notes.

This is especially for noting the switch to sql and
explaining how to convert your mongodb data over to sql.

docs/source/index.rst

@@ -31,6 +31,7 @@ Table of Contents:
    configuration
    media-types
    help
+   relnotes
    theming
    codebase
 

docs/source/relnotes.rst

@@ -0,0 +1,52 @@
+.. MediaGoblin Documentation
+
+   Written in 2012 by MediaGoblin contributors
+
+   To the extent possible under law, the author(s) have dedicated all
+   copyright and related and neighboring rights to this software to
+   the public domain worldwide. This software is distributed without
+   any warranty.
+
+   You should have received a copy of the CC0 Public Domain
+   Dedication along with this software. If not, see
+   <http://creativecommons.org/publicdomain/zero/1.0/>.
+
+=============
+Release Notes
+=============
+
+This chapter has important information for releases in it.
+If you're upgrading from a previous release, please read it
+carefully, or at least skim over it.
+
+
+0.3.0
+=====
+
+This release has one important change. You need to act when
+upgrading from a previous version!
+
+This release changes the database system from MongoDB to
+SQL(alchemy). If you want to setup a fresh instance, just
+follow the instructions in the deployment chapter. If on
+the other hand you want to continue to use one instance,
+read on.
+
+To convert our data from MongoDB to SQL(alchemy), you need
+to follow these steps:
+
+1. Make sure your MongoDB is still running and has your
+   data, it's needed for the conversion.
+
+2. Configure the sql_engine URI in the config to represent
+   your target database (see: Deployment docs)
+
+3. You need an empty database.
+
+4. Then run the following command::
+
+    bin/gmg [-cf mediagoblin_config.ini] convert_mongo_to_sql
+
+5. Start your server and investigate.
+
+6. That's it.